The use of traditional bricks-and-mortar construction presents some well-known limitations in building. These limitations include the need for skilled labour to achieve an even, square result; limitations in the speed at which a structure can be erected due, for instance, to the requirement for mortar to cure; and limitations in the compressive load carrying ability of the structure due to the variation in stiffness between bricks and mortar.
The use of pre-cast concrete panels has become more common in recent years, in an attempt to ameliorate some of these limitations. The use of such panels has its own limitations, including difficulties in adapting panels to a particular site, and the need for mechanised equipment during movement and installation of the panels.
In another alternative to traditional bricks-and-mortar construction, interlocking building blocks have been used in some applications. One example of this is the Haener block, shown in U.S. Pat. No. 3,888,060. The Haener block has interlocking tongue-and-groove style projections between adjacent blocks. Also available are building blocks having projections on one side and corresponding recesses on an opposing side. An example is the Habegger block, shown in U.S. Pat. No. 4,124,961. This style of block has complementary upper and lower surfaces, with projections on a lower surface which locate within hollows on an upper surface.
The advantage of interlocking building blocks is that they are largely self-locating, and do not require mortar, thus allowing for the quick erection of structures by largely unskilled labour.
It is also known to use interlocking blocks in the laying of segmental block paving. Traditional paving methods rely on frictional engagement between adjacent paving bricks to prevent movement of the paving under load. The effectiveness of this is reliant on many factors, including the paver shape, the laying pattern, and the properties of the joint sand and the bedding sand. These factors are difficult to quantify and thus control.
In an attempt to ameliorate these problems, systems of interlocking blocks, such as those described in U.S. Pat. No. 6,988,847, have been employed as paving blocks.
All of the interlocking block systems described above have been designed to suit a specific construction purpose. It is considered desirable to create a construction block design which can be used for both building and paving, as well as other applications. The present invention seeks to meet this desire.
The present invention employs the principle of topological interlocking, where surfaces of adjacent blocks are of complementary shape. An example of this principle can be found in GB 1,533,980, which proposes building blocks having sides which follow a sinusoidal curve.
A significant limitation of this design is that unless adjacent blocks are perfectly aligned, significant stress concentrations can occur at the resulting point or line loading points. The design also requires a high degree of accuracy in manufacture. The present invention proposes an alternative construction block design in light of the difficulties of the prior art.